1. Field of the Invention
The present invention relates to a fixed aperture, compact camera for photographically copying a portion of an illuminated image, in general, and to a manually adjustable exposure control system for such a camera, in particular.
2. Description of the Prior Art
At the present time there is a fairly large need for a relatively simple, portable and compact camera that is capable of expeditiously making a photograph or hard copy of all or a selected portion of an illuminated transparent image. In the medical field, for example, it is fairly normal practice to make a multiple image set of x-rays or film transparencies of selected views of a patient's anatomy in order to provide a treating (or consulting) physician with an additional tool for diagnosing the patient's illness. Standard practice in such instances is to provide a single copy of each anatomical view produced by x-ray, or other imaging means, for inclusion in the patient's case file.
Typically, a treating physician views 14.times.17 inch transparencies wherein each transparency includes a single x-ray image or multiple smaller images produced either by Computed Tomography (CT) or Magnetic Resonance Imaging (MRI). In many (if not all) instances, the treating physician would like to have a copy of one or two individual images or portions thereof per patient case that best establishes the diagnosis of pathology (or normalcy) for his own records and for the records of a consulting physician. It is only in rare instances where a physician needs a complete imagery set for his own records. To obtain such individual images today is an unwieldy, time consuming and expensive process, even at a very large medical facility, and is therefore rarely used.
There is a major disadvantage associated with a physician's inability to promptly obtain a copy of selected portions of his patient's diagnostic images. These images theoretically belong to the patient, and in a medical facility access to them is generally controlled by the radiology department. With very large numbers of diagnostic image sets to take care of, it is not uncommon for the radiology department in such a facility to lose or temporarily misplace a substantial number of the diagnostic images placed in its care. Therefore, if a physician is not able to obtain a copy of the pertinent images during the relatively short period of time that he has personal contact with the entire case file, i.e., while he is diagnosing or formally consulting, it is highly unlikely that he will have easy access to these images at some time in the future. The lack of easy and repeated access to a patient's diagnostic images is a fairly common problem in the medical field.
A compact, hand-held camera for photographing an illuminated image, such as that formed by x-rays on a film transparency, is described in commonly assigned, copending U.S. patent application Ser. No. 202,480, filed June 6, 1988 by W. Hudspeth. The camera functions, in part, by placing an opening in the camera's housing, through which a photographic image is formed, directly over that portion of the total illuminated image selected to be photographed and in direct contact with the film transparency. This particular camera owes its compactness, in large part, to the use of an optical path shortening graded-index microlens array that couples a selected film transparency portion to be photographed, to the camera's film plane. The microlens array is driven across the above-noted opening by a manually controlled, variable-speed, dc motor for the purpose of transferring an illuminated image present at this opening to a photosensitive material located in an exposure position at the camera's film plane. The camera operator selects the desired microlens array scanning speed, prior to exposure, based on is subjective determination as to the intensity of the light illuminating the image to be copied. If the transparency is over-illuminated, the microlens array is driven across the opening through which a photographic image is formed at a relatively fast speed, whereas the microlens array is driven across this opening a relatively slow speed if the transparency is under-illuminated. While this type of exposure control system is quite effective, the component parts thereof such as the variable speed motor and controls therefor introduce a significant cost penalty into the overall cost of the camera.